BLACKSBURG, Va. — George Allen and Tim Kaine, both former governors of Virginia, immediately tossed away their gloves in the final debate in their closely watched U.S. Senate race, throwing haymakers and lobbing charges that each is an immutable partisan and misguided on the economy, spending, and defense.

Mr. Allen charged out of the gate with the seemingly innocuous statement that he wanted to be “Virginia’s senator.”

“Tim wants to be President Obama’s senator,” Mr. Allen continued at the debate, held Thursday night on the Virginia Tech campus. “In Washington, you deserve a strong, independent voice, not an echo.”

Mr. Kaine, though, pointed to one of the least-likely allies for a Democrat — former President George W. Bush — as evidence to the contrary.

“I do not think it is anti-Virginia to support the president of the United States,” said Mr. Kaine, noting that he worked with Mr. Bush on the Rail-to-Dulles project in Northern Virginia and in the aftermath of the 2007 Virginia Tech massacre.

Mr. Allen has made fighting $500 billion in looming defense cuts a key issue of his campaign and invoked the issue multiple times Thursday. The cuts are part of the so-called “sequestration” package that resulted when a congressional supercommittee, created as part of a deal last summer to raise the country’s debt ceiling, failed to agree on $1.2 trillion in spending cuts.

Mr. Allen said repealing Mr. Obama’s health care overhaul; ferreting out waste, fraud and abuse in the federal government, and unleashing more of America’s energy resources could go toward plugging the gap.

“I have a son who just started a career in the military,” replied Mr. Kaine, whose campaign has argued that repealing the health care overhaul would raise the deficit, not lower it. “I’m not going to do anything to hurt the troops or hurt the vets.”

Mr. Kaine has called for an approach that let allow the Bush-era tax cuts expire on incomes of more than $500,000, eliminate subsidies for big oil companies, and allow the government to negotiate prescription-drug prices with pharmaceutical companies on behalf of senior citizens.

Other attacks mirrored the ones the two candidates leveled at one another in their Oct. 8 debate in Richmond, with Mr. Allen hammering Mr. Kaine for accepting the job of Democratic National Committee chairman while serving his final year as governor of Virginia. Mr. Kaine, meanwhile, tried to paint Mr. Allen as a politician who would serve as little more than an obstructionist unwilling to compromise, dredging up derogatory comments he has made about Democrats in the past.

Fiscal issues were also equal opportunity fodder. Mr. Allen blasted Mr. Kaine for repeatedly proposing tax increases while governor, while Mr. Kaine pointed out that Mr. Allen, who served in the U.S. Senate from 2001 to 2007, was a willing participant in a Congress that racked up trillions in debt via the Bush-era tax cuts, wars in Iraq and Afghanistan and a prescription-drug entitlement for seniors.

Neither candidate, however, was quick to answer the question of whether he would support the Simpson-Bowles deficit reduction plan, which failed to advance past a commission created by Mr. Obama. The politically touchy plan contains tax increases that are anathema to Republicans and changes to entitlements and Social Security that Democrats reject.

“The president walked away from it as if it was a dead animal on the front porch,” Mr. Allen said, elaborating that he would “amend” the plan and did favor eliminating loopholes in the country’s tax law.

Mr. Kaine said he would back a plan “like” Simpson-Bowles that includes two or three dollars in spending cuts for every dollar in revenue increases, but, as is, he would not support it because he disagreed with the plan’s specific changes to Social Security.

Both campaigns largely have shrugged off polls that appeared to give Mr. Kaine a slight edge in recent weeks, insisting that the race would remain within the margin of error to Election Day. Indeed, the latest Real Clear Politics average of Virginia polls gives Mr. Kaine a 2.2-point lead, at 47.6 percent to 45.4 percent — less than most polls’ error margins and with both men still well below the all-important 50 percent mark.

The contest between Mr. Kaine and Mr. Allen has seen more spending from outside groups than any other U.S. Senate race in the country — more than $22 million, according to the Center for Responsive Politics. With Democrats holding an effective 53-47 majority in the Senate, the race is one of a handful that could well determine which party controls the body come January.

When Mr. Allen officially entered the race nearly two years ago, he thought he was going to have a rematch with Democratic Sen. Jim Webb, who narrowly defeated him in 2006. But when Mr. Webb opted not to run for a second term, Mr. Kaine stepped in after Democrats across the state pushed the former governor to run.